Disclosed is a method and apparatus for encoding speech with correct encoding of silence periods. In the disclosed apparatus, the speech signal is processed in contiguous blocks, and each block is tested, by evaluating a window of blocks in the neighborhood of the tested block, to determine whether the tested block represents a silence interval. When it is determined that a processed block represents silence, the processed block is forced to encode as a perfect silence. This forcing is accomplished by substituting the encoded block with a preselected silence sequence of alternating "1" and "0" strings.